Transmission shifting arrangement

Abstract

Shifting arrangement for a gear transmission constructed in sections to be used for vehicles. With a common manual clutch (2) a parking lock, a reversing transmission and a range-change transmission are shifted. The movements of the manual clutch (2) in the shifting direction, respectively in the longitudinal direction of the vehicle, actuate in a purely mechanical manner the shifting of the parking lock and the reversing transmission. Movements of the manual clutch (2) in selection direction, respectively transversally to the longitudinal direction of the vehicle, actuate mechanically and hydraulically the shifting of the range-change transmission. Mechanical locking devices prevent undesired shifting.

We claim: 
     
       1. In a shifting arrangement for a gear transmission, particularly for agricultural vehicles, constructed in section, with a reversing transmission and a range-change transmission, with a manual clutch movable at least in three shifting paths parallel to each other in shifting direction and perpendicularly thereto in selection direction, cooperating with a gear-shift-lever shaft whose motion in the shifting direction actuates the shifting of the reversing transmission and whose motion in the selection direction actuates a shifting of the range-change transmission, with a shift finger mounted on the gear-shift-lever shaft, with a first shift fork for the shifting of the reversing transmission and a second shift fork for the shifting of the range-change transmission, the improvement wherein means is provided to define two immediately adjacent shift paths for the finger in which the finger actuates the shift fork of the reversing transmission and a third shifting path for the finger in which the finger actuates an entrainment element for the shifting of a lock in parking position,   the gear-shift-lever shaft has an entrainment element rigidly connected thereto and formed with a control surface,   the control surface is a surface of a cylinder concentric to the gear-shift-lever shaft, said surface having an axial control groove and on a common generatrix a sequence switch cam,   the control surface actuates a valve slide of a multiway valve,   the valve slide is always pressed against the control surface by spring pressure,   the valve slide assumes a median neutral position in which the multiway valve closes a supply duct coming from a fluid source and connects two connecting ducts of a double-acting shifting cylinder with a tank when the valve slide is pressed against the cylindrical surface of the control surface,   the valve slide occupies one of two end positions, wherein the multiway valve connects one of the two connecting ducts of the shifting cylinder with the fluid source and the other two connecting ducts with a tank when the valve slide selectively projects into the guide groove and rests against the sequence switch cam, and   the shifting cylinder actuates the shift fork of the range-change transmission.   
     
     
       2. The improvement defined in claim 1 wherein the manual clutch is rigidly connected to the gear-shift-lever shaft. 
     
     
       3. The improvement defined in claim 1 wherein the movements of the shift finger and of parts rigidly connected thereto are guided and limited by a shifting gate rigidly fastened to a housing. 
     
     
       4. The improvement defined in claim 1 wherein a piston of the shifting cylinder is rigidly connected with the shift fork of the range-change transmission. 
     
     
       5. The improvement defined in claim 1 wherein the valve slide can occupy one of its two end positions when the shift finger is in the selector path. 
     
     
       6. The improvement defined in claim 1 wherein the shift fork of the range-change transmission carries a locking element,   the gear-shift-lever shaft or the entrainment means rigidly thereto connected has a locking surface,   the locking surface is a cylindrical surface concentric to the gear-shift-lever shaft, provided with an axial locking groove,   a locking pin is always pressed against the locking surface by spring force,   the locking pin in a first locking position when supported by the locking element and lowered into the axial locking groove prevents a rotation of the gear-shift-lever shaft, as long as the shift fork of the range-change transmission has not yet reached one of its two end positions,   the locking pin in a second locking position, supported by the cylinder surface of the locking surface and lowered at one of the two sides of the locking element maintains the shift fork of the range-change transmission in one of its both end positions, as long as the gear-shift-lever shaft is rotated so that the shift finger is out of the selector path.   
     
     
       7. The improvement defined in claim 1 wherein a third shift fork or a locking bar slidable by the shift fork against spring force is provided with a locking step,   the gear-shift-lever shaft or an entrainment means rigidly connected thereto is provided with a locking surface,   the locking surface is a cylinder surface concentric to the gear-shift-lever shaft and presents a circumferentially running locking groove,   a locking pin is always pressed against the locking surface by spring force,   the locking pin in a first locking position supported by the locking step and lowered into the circumferentially running locking groove, prevents the axial displacement of the gear-shift-lever shaft, as long as the shift fork is in a low-speed step of a creep-speed gear,   the locking pin in a second locking position supported by the cylinder surface of the locking surface and projecting in front of the locking step maintains the shift fork in the position for the high-speed step of the creep speed gear, as long as the shift finger rigidly connected to the gear-shift-lever shaft has not yet reached the shifting path for the low-speed step of the range-change transmission.